How do you animate more than one Rigify rig in a single scene?
As Rigify is based on Blender's internal drivers, constraints, and scripts, it's not directly exportable to Unity, so you should think of it as a Blender instrument.
The common workflow is to program the animation into Blender, using two different Rigify rigs (use the advanced options, near to the generate rig button, to give an unique name to every rig).
When the animation is finished you can turn on the Deforming bones layer only, select all deforming bones (bone layer 29, counting from 00 to 31, all bones have the &quot;DEF-&quot; suffix), and in pose mode go to the menu pose &gt; animation &gt; bake action (turn on all the preferences), so that a copy of the rig, maden of deforming bones only, with baked action, can be directly exported to Unity.
Usually we use two rigs for two characters, but if you really want a single action, at this stage you can join (Ctrl J) the two only deforming bones rigs: all bones names and animation channels will update adding the .001 suffix to the joined copy.